William Kingdon Clifford

Our lives are guided by that general conception of the course of things which has been created by society for social purposes.

No real belief, however trifling and fragmentary it may seem, is ever truly insignificant; it prepares us to receive more of its like, confirms those which resembled it before, and weakens others; and so gradually it lays a stealthy train …

He who truly believes that which prompts him to an action has looked upon the action to lust after it, he has committed it already in his heart.

No man holding a strong belief on one side of a question, or even wishing to hold a belief on one side, can investigate it with such fairness and completeness as if he were really in doubt and unbiased; so that the existence of a belief …

It might be said to the agitator, "However convinced you were of the justice of your cause and the truth of your convictions, you ought not to have made a public attack upon any man's character until you had examined the evidence on both …

Is a physical force, such as the attraction of earth, analogous to our "exertion of force" in muscular work? No, for the sensation of muscular effort is complicated. It involves nerve and muscle, which we know not to be present in the …

Energy of position, defined by the statement of the law that the work done in getting from one position to another is the same by whatever path the change of position is made.

'. In the burning of coal there is a falling together of carbon and oxygen [and heat is produced] but we do not know in which of the two forms, if either, the energy which comes out as heat existed in the chemical process. For such a case …

', which we find by experiment

energy is conserved, or is indestructible. This form of speech might be applied to other cases of alternate immortality, where one of two things comes into existence on disappearance of the other.

Energy is a quantity which can be greater or less but has no direction.

Energy [is of two kinds: 1. Energy of motion; 2. Energy of position].

Force, defined as above, is not conserved at all. It may appear and disappear; it is continually being created and destroyed. "Conservation of force" is, mathematically speaking, a contradiction in terms.

it is a quantity having direction.

depending upon its position relative to other things.

depends on the position of surrounding bodies, and may be described as the change of momentum of a body

In all cases change of motion is connected by invariable laws with the position of surrounding bodies. Force

Force cannot be explained without stating a law of nature concerning momentum

' may be roughly described as quantity motion. A body moving at a speed of say twenty an hour, has a certain quantity of motion. If the body goes forty miles an hour there is twice as motion; or if twice as much matter goes twenty miles …

Causation is defined by some modern philosophers as unconditional uniformity of succession, e.g., existence of fire follows from putting a lighted match to the fuel. This idea must be got rid of to understand force. All universally true …

No mathematician can give any meaning to language about matter, force, inertia, used in text-books of mechanics.

I am endeavouring in a general way to explain the laws of double refraction on this hypothesis, but have not yet arrived at any results sufficiently decisive to be communicated.

in proportion to his colossal ignorance is the perfection and symmetry of the system which he sets up; because it is so much easier to put an empty room tidy than a full one.

There is in the true man of science a desire stronger than the wish to have his beliefs upheld; namely, the desire to have them true.